Acousto-optic Modulator - Modelocking

Modelocking

Acousto-optic modulators are much faster than typical mechanical devices such as tiltable mirrors. The time it takes an AOM to shift the exiting beam in is roughly limited to the transit time of the sound wave across the beam (typically 5 to 100 nanoseconds). This is fast enough to create active modelocking in an ultrafast laser. When faster control is necessary electro-optic modulators are used. However, these require very high voltages (e.g. 1-10 kilovolts), whereas AOMs offer more deflection range, simple design, and low power consumption (less than 3 watts).